On the standard model and parity conservation

2016

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In the SM gauge symmetries and fermion content of neutrinos, charged leptons and quarks, we study the effective four-fermion operators of Einstein-Cartan type and their contributions to the Schwinger-Dyson equations of fermion self-energy functions. The study is motivated by the speculation that these four-fermion operators are probably originated due to the quantum gravity that provides the natural regularization for chiral-symmetric gauge field theories. In the chiral-gauge symmetry breaking phase, as to achieve the energetically favorable ground state, only the top-quark mass is generated via the spontaneous symmetry breaking, and other fermion masses are generated via the explicit symmetry breaking induced by the top-quark mass, four-fermion interactions and fermion-flavor mixing matrices. A phase transition from the symmetry breaking phase to the chiral-gauge symmetric phase at TeV scale occurs and the drastically fine-tuning problem can be resolved. In the infrared fixed-point domain of the four-fermion coupling for the SM at low energies, we qualitatively obtain the hierarchy patterns of the SM fermion Dirac masses, Yukawa couplings and family-flavor mixing matrices with three additional right-handed neutrinos $\nu^f_R$. Large Majorana masses and lepton-symmetry breaking are originated by the four-fermion interactions among $\nu^f_R$ and their left-handed conjugated fields $\nu^{fc}_R$. Light masses of gauged Majorana neutrinos in the normal hierarchy ($10^{-5}-10^{-2}$ eV) are obtained consistently with neutrino oscillations. We present some discussions on the composite Higgs phenomenology and forward-backward asymmetry of $t\bar t$-production, as well as remarks on the candidates of light and heavy dark matter particles (fermions, scalar and pseudoscalar bosons).Comment: In this article, the study of the third fermion family (arXiv1506.05994 PRD93, 073001 (2016)) is generalized to the three fermion families. This is an updated version 52 pages, 8 Figures and 2 table

Section: B W ± -Boson Coupling To Right-handed Fermionsmentioning

confidence: 99%

Hierarchy spectrum of SM fermions: from top quark to electron neutrino

2016

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“…In this UV-domain at high energies, it realizes an effective theory of composite bosons and fermions composed by SM elementary fermions, these composite particles and their interactions preserving the SM gauge symmetries [14][15][16][17][18][19][20]. This is the issue that we would like to focus in this article.…”

Section: Strong-interacting Four-fermion Operators and Gauge-symmetrimentioning

confidence: 99%

“…their couplings to the SU L (2)-gauge bosons [16][17][18][19]. Detailed calculations can be found in these references and their appendices.…”

Section: Jhep05(2017)146mentioning

confidence: 99%

“…In the gauge symmetric phase of an SU L (2)-chiral gauge theory containing the four-fermion operator (3.8), the composite particles and 1PI vertex functions, as well as their properties in the UV-domain were analyzed by using the approach of strong-coupling expansion to the dynamics of four-fermion operators at the cutoff Λ [14,15,[17][18][19][20][21]. In this section, however, based on the effective Einstein-Cartan Lagrangian (2.6) in the SM framework, see section 2.4, we are going to show the composite-particle spectrum and 1PI interaction (effective Lagrangian) in terms of the quantum numbers of SM gauge symmetries.…”

Section: Jhep05(2017)146 4 Composite Particles and Effective Lagrangimentioning

confidence: 99%

“…Last but not least, all sterile neutrinos (ν i R , ν ic R ) and SM gauge-singlet (neutral) states of massive composite fermions, e.g., Ψ D ∼ [ν ℓ R , (l i L ν ℓ R )ℓ Li ], can be possible candidates of warm and cold dark matter [19,21]. They can couple or decay into the SM elementary particles in the following ways.…”

Section: Sterile Neutrinos Interacting With Sm Particles At High Enermentioning

confidence: 99%

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An effective strong-coupling theory of composite particles in UV-domain

2017

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We briefly review the effective field theory of massive composite particles, their gauge couplings and characteristic energy scale in the UV-domain of UV-stable fixed point of strong four-fermion coupling, then mainly focus the discussions on the decay channels of composite particles into the final states of the SM gauge bosons, leptons and quarks. We calculate the rates of composite bosons decaying into two gauge bosons γγ, γZ 0 , W + W − , Z 0 Z 0 and give the ratios of decay rates of different channels depending on gauge couplings only. It is shown that a composite fermion decays into an elementary fermion and a composite boson, the latter being an intermediate state decays into two gauge bosons, leading to a peculiar kinematics of final states of a quark (or a lepton) and two gauge bosons. These provide experimental implications of such an effective theory of composite particles beyond the SM. We also present some speculative discussions on the channels of composite fermions decaying into W W , W Z and ZZ two boson-tagged jets with quark jets, or to four-quark jets. Moreover, at the same energy scale of composite particles produced in high-energy experiments, composite particles are also produced by high-energy sterile neutrino (dark matter) collisions, their decays lead to excesses of cosmic ray particles in space and signals of SM particles in underground laboratories.

Shedding new light on sterile neutrinos from XENON1T experiment

Shakeri

Hajkarim

2020

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The XENON1T collaboration recently reported the excess of events from recoil electrons, possibly giving an insight into new area beyond the Standard Model (SM) of particle physics. We try to explain this excess by considering effective interactions between the sterile neutrinos and the SM particles. In this paper, we present an effective model based on one-particle-irreducible interaction vertices at low energies that are induced from the SM gauge symmetric four-fermion operators at high energies. The effective interaction strength is constrained by the SM precision measurements, astrophysical and cosmological observations. We introduce a novel effective electromagnetic interaction between sterile neutrinos and SM neutrinos, which can successfully explain the XENON1T event rate through inelastic scattering of the sterile neutrino dark matter from Xenon electrons. We find that sterile neutrinos with masses around 90 keV and specific effective coupling can fit well with the XENON1T data where the best fit points preserving DM constraints and possibly describe the anomalies in other experiments.